In 1990, there was a 10% increase in the incidence of tuberculosis in the United States. In addition, there has been an increase in the appearance of clinical isolates of tuberculosis that are resistant to antibiotics used to treat the disease. This problem is exacerbated by the length of time that is currently needed both to diagnose tuberculosis, and to determine the drug susceptibilities of various strains of M. tuberculosis. As a result, patients with M. tuberculosis may remain infectious for long periods of time without being treated, or may be treated with a drug to which the bacterial strain is resistant. Therefore, a need has arisen in the field for a method of diagnosis of M. tuberculosis (and other mycobacterial infections) which is rapid, sensitive and specific, which method is also capable of assessing the drug susceptibilities of the various strains of M. tuberculosis and other mycobacterial strains. It is critical that a mycobacterial strain be assessed for drug resistance rapidly because a patient infected with a strain of M. tuberculosis or another mycobacteria must be treated immediately with the particular antibiotic drug(s) to which the strain is not resistant, and not with antibiotic drug(s) to which the strain is resistant, or the patient may die.
Currently, the most rapid test available for the diagnosis of M. tuberculosis is the staining of sputum samples for acid-fast bacilli, which is a tedious procedure, and which procedure has low sensitivity. Alternative methods for diagnosis require cultivation of the bacilli for approximately two to six weeks followed by classification of the cultured organism. Typical diagnostic tools include biochemical tests, analysis of mycolic acids and serotyping. All of these tests are time-consuming. More recently, the use of oligonucleotide probes and Polymerase Chain Reaction have been suggested for the identification of M. tuberculosis species. Although these methods may be useful approaches, their uses in a clinical setting have not yet been determined. Further, these methods do not distinguish between live and dead organisms, and are therefore of limited use in the determination of drug sensitivities of clinical isolates.
In addition, Mycobacterium avium (M. avium) is a mycobacteria which is often found in immunosuppressed patients. This mycobacteria is typically disseminated throughout the bodies of immunosuppressed patients, such as AIDS patients, and causes M. avium infection. Because this mycobacteria often causes death in immunosuppressed patients, it is necessary to be able to diagnose and assess the drug susceptibilities of the various strains of M. avium.
It is therefore an object of this invention to construct broad mycobacterial host range and mycobacterial species-specific reporter mycobacteriophages.
It is another object of this invention to provide mycobacterial species-specific reporter mycobacteriophages which may be used to rapidly diagnose mycobacterial infections.
It is still another object of this invention to provide mycobacterial species-specific reporter mycobacteriophages which may be used to rapidly assess the drug susceptibilities of different strains of mycobacteria in clinical samples.
It is yet another object of this invention to provide mycobacterial species-specific reporter mycobacteriophages wherein the reporter genes are luciferase genes, which mycobacterial species-specific reporter mycobacteriophages may be used to rapidly diagnose mycobacterial infections and to rapidly assess the drug susceptibilities of various strains of mycobacteria.
It is a further object of this invention to provide mycobacterial species-specific luciferase gene reporter mycobacteriophages which may be used to rapidly diagnose tuberculosis and assess the drug susceptibilities of the various strains of M. tuberculosis.